Mac下Eclipse提交任务到Hadoop集群

搭建Hadoop集群: VirtualBox+Ubuntu 14.04+Hadoop2.6.0

搭建好集群后, 在Mac下安装Eclipse并链接Hadoop集群

1. 访问集群

1.1. 修改Mac的hosts

添加Master的IP到Mac的hosts

##
# Host Database
#
# localhost is used to configure the loopback interface
# when the system is booting.  Do not change this entry.
##
127.0.0.1    localhost
255.255.255.255    broadcasthost
::1             localhost

192.168.56.101  Master # 添加Master的IP

1.2 访问集群

Master下, 启动集群
Mac下, 打开http://master:50070/
可以成功访问, 看到集群的信息, 就能够了

2. 下载安装Eclipse

Eclipse IDE for Java Developers

http://www.eclipse.org/downloads/package...

3. 配置Eclipse

3.1 配置Hadoop-Eclipse-Plugin

3.1.1 下载Hadoop-Eclipse-Plugin

可下载 Github 上的 hadoop2x-eclipse-plugin（备用下载地址：http://pan.baidu.com/s/1i4ikIoP）

3.1.2 安装Hadoop-Eclipse-Plugin

在Applications中找个Eclise, 右键, Show Package Contents

将插件复制到plugins目录下, 而后从新打开Eclipse就能够了

3.2 链接Hadoop集群

3.2.1 配置Hadoop安装目录

将Hadoop安装包解压到任何目录, 不用作任何配置, 而后在Eclipse中指向该目录便可

3.2.2 配置集群地址

点击右上角的加号

添加Map/Reduce视图

选择Map/Reduce Locations, 而后右键, 选择New Hadoop location

须要改Location name, Host, DFS Master下的Port, User name ( Master会引用Mac中的hosts配置的IP ), 完成后, Finish

3.2.3 查看HDFS

查看是否能够直接访问HDFS

4. 集群中运行WordCount

4.1 建立项目

File -> New -> Other -> Map/Reduce Project

输入项目名: WordCount, 而后点击, Finish

4.2 建立类

建立一个类, 报名org.apache.hadoop.examples, 类名: WordCount

4.3 WordCount代码

复制下面的代码到WordCount.java中

package org.apache.hadoop.examples;
 
import java.io.IOException;
import java.util.StringTokenizer;
 
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.GenericOptionsParser;
 
public class WordCount {
 
  public static class TokenizerMapper 
       extends Mapper<Object, Text, Text, IntWritable>{
 
    private final static IntWritable one = new IntWritable(1);
    private Text word = new Text();
 
    public void map(Object key, Text value, Context context
                    ) throws IOException, InterruptedException {
      StringTokenizer itr = new StringTokenizer(value.toString());
      while (itr.hasMoreTokens()) {
        word.set(itr.nextToken());
        context.write(word, one);
      }
    }
  }
 
  public static class IntSumReducer 
       extends Reducer<Text,IntWritable,Text,IntWritable> {
    private IntWritable result = new IntWritable();
 
    public void reduce(Text key, Iterable<IntWritable> values, 
                       Context context
                       ) throws IOException, InterruptedException {
      int sum = 0;
      for (IntWritable val : values) {
        sum += val.get();
      }
      result.set(sum);
      context.write(key, result);
    }
  }
 
  public static void main(String[] args) throws Exception {
    Configuration conf = new Configuration();
    String[] otherArgs = new GenericOptionsParser(conf, args).getRemainingArgs();
    if (otherArgs.length != 2) {
      System.err.println("Usage: wordcount <in> <out>");
      System.exit(2);
    }
    Job job = new Job(conf, "word count");
    job.setJarByClass(WordCount.class);
    job.setMapperClass(TokenizerMapper.class);
    job.setCombinerClass(IntSumReducer.class);
    job.setReducerClass(IntSumReducer.class);
    job.setOutputKeyClass(Text.class);
    job.setOutputValueClass(IntWritable.class);
    FileInputFormat.addInputPath(job, new Path(otherArgs[0]));
    FileOutputFormat.setOutputPath(job, new Path(otherArgs[1]));
    System.exit(job.waitForCompletion(true) ? 0 : 1);
  }
}

4.4 配置Hadoop参数

将全部修改过的配置文件和log4j.properties, 复制到src目标下

这里我复制了slaves, core-site.xml, hdfs-site.xml, mapred-site.xml, yarn-site.xml

4.4 配置HDFS输入输出路径

鼠标移动到WordCount.java上, 右键, Run As, Java Application

此时, 程序不会正常运行. 再次右键, Run As, 选择Run Configurations

填入输入输出路径 (空格分割)

配置完成后点击, Run. 此时会出现, Permission denied

5. 运行中出现的问题

5.1 Permission denied

没有权限访问HDFS

# 假设Mac的用户名为hadoop
groupadd supergroup # 添加supergroup组
useradd -g supergroup hadoop # 添加hadoop用户到supergroup组

# 修改hadoop集群中hdfs文件的组权限, 使属于supergroup组的全部用户都有读写权限
hadoop fs -chmod 777 /

6. 查看Hadoop源码

6.1 下载源码

http://apache.claz.org/hadoop/common/had...

6.2 连接源码

右上角的搜索框中, 搜索Open Type

输入NameNode, 选择NameNode, 发现看不了源码

点击Attach Source -> External location -> External Floder

参考资料

使用Eclipse编译运行MapReduce程序 Hadoop2.6.0_Ubuntu/CentOS